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What to see

In the neighbouring checkerboard you can see a central “bulge”. This bulge is illusionary: the checkerboard is fully regular and each check is square, as becomes obvious when the small ticks are not present.

You can use the sliders or the colour pickers to try out various combination. This also stops the automatic slider change.

First you might like to flip through the presets (below “default”) using the pop-up menu at top right. The “no ticks” setting shows the raw checkerboard. “Low contrast” does not impair the 3D impression. Interestingly, with the right relative lightness, settings one can change the bulge into a “pinch”.